20 + 30 + 40 + 50 + 60 + 70
= ( 70 + 30 ) + ( 40 + 60 ) + (20 + 50 )
= 100 + 100 + 70
= 200 + 70
= 270
Tk mk nha m.n !! ^^
20+30+40+50+60+70=?
